Hi, Everyone before we start, We have to know what SSH is. 

SSH stands for "Secure Shell." Cryptographic network protocol provides a secure way to access and manage remote devices or servers over an unsecured network, such as the Internet. SSH is commonly used for safe remote administration, file transfers, and other network services.

SSH provides the following key features:

Encryption:  All communication between the client and the server is encrypted, which ensures that sensitive information, such as passwords and data, cannot be intercepted and understood by unauthorized parties.

Authentication: SSH uses various methods of authentication, such as passwords, public key cryptography, and keyboard-interactive authentication, to verify the identity of users and ensure that only authorized users can access the remote server.

Data Integrity: SSH ensures the integrity of the data being transferred, meaning that the data remains unchanged during transmission and is not tampered with by malicious entities.

Port Forwarding: SSH supports port forwarding, which allows users to securely forward network connections from their local machine to a remote server or vice versa. This can be useful for accessing services that are not directly accessible due to firewall restrictions or for encrypting otherwise unsecured connections.

Remote Access: SSH allows administrators and users to access and manage remote servers and devices as if they were directly connected to them. This is particularly useful for managing servers located in data centers or remote locations.

Now questions about how to install ssh on ubuntu 20.4

Open terminal 

1. sudo apt update

2. sudo install openssh-server

3. sudo systemctl status ssh

4. sudo ufw allow ssh

How to access it? 

ssh username@ipaddress

then ask password .. type your password 

Example ubuntu@203.156.78.45